Memoir to Accompany a Map of the Magnetic Variation for 1840 in the Atlantic Ocean between the Parallels of 60 degrees N. and 60 degrees S. Latitude, Being Contributions to Terrestrial Magnetism, No. 9

E. Sabine
1843 Proceedings of the Royal Society of London  
doi:10.1098/rspl.1843.0195 fatcat:4bnbhkhjgvcudahmqrpbmwprwq